­Onboard the starship Enterprise, you're hanging out with the crew members, enjoying a game of poker. You're traveling at impulse speed during a leisurely deep-­space exploration, and everyone has some downtime. But wait -- all of a sudden, the ship receives an urgent message from a Federation admiral, informing th­e crew of an outbreak of war in the Neutral Zone. The Enterprise is ordered to report to the situation as soon as possible. The area in question is about 20 light years (117 trillion kilometers) away, but this is no problem in the "Star Trek" universe. The captain adjusts the ship's warp drive appropriately, and you settle in for warp speed. Traveling faster than the speed of light, you should arrive to your destination in just a few minutes.

­For as long as humans have looked up to the skies, space has fascinated us, and astronomers and philosophers alike have asked the most fundamental questions while staring at the stars. What are we doing here, anyway? How did the universe begin, and are there other, parallel universes that mirror ours? Is there life out there in other galaxies, and what would it be like to travel there?
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While we haven't quite answered these questions yet, we at least have science fiction like "Star Trek" to test the human imagination. Everything from H.G. Wells' "The Time Machine" to "Star Trek" to Joss Whedon's "Firefly" series has touched on the possibilities of time travel, teleportation and, of course, warp speed. But how does something like warp speed fit into reality and our universe? Is warp speed just a wacky science fiction device, or is it theoretically possible? How does it work in the "Star Trek" universe? For everything on warp speed, infinity and beyond, read the following pages.

Newton's Third Law of Motion

Hulton Archive/Getty Images"Star Trek" had William Shatner as Captain James T. Kirk, but whatever were they going to do about intergalactic space travel?

When the writers of "Star Trek" sat down to plan the series, they found themselves confronted with a few problems. They were essentially creating a space opera, a subgenre of science fiction that takes place in space and covers the span of several galaxies and millions of light years. The "Star Wars" films are another example of the space opera subgenre. As the "opera" part of the name suggests, a show like "Star Trek" isn't meant to be slow or ordinary -- when people think of the series, they probably think of melodramatic plots involving aliens, space travel and action-packed laser fights.

So the creator of the series, Gene Roddenberry, and the other writers had to find a way to move the show's characters around the universe in a timely, dramatic fashion. At the same time, they wanted to do their best to stick to the laws of physics. The biggest problem was that even if a starship could travel at the speed of light, the time to go from one galaxy to another could still take hundreds, maybe thousands of years. A journey from the Earth to the center of our galaxy, for example, would take about 25,000 years if you were to travel just under the speed of light. This, of course, wouldn't make very exciting television.

The invention of warp speed solved the opera part of the problem, since it allowed the Enterprise to go much faster than the speed of light. But what was the explanation? How could they explain an object traveling faster than the speed of light, something Einstein proved impossible in his Special Theory of Relativity?

Eliot J. Schechter/Getty ImagesWhen this shuttle makes its way into orbit, it will travel at about 17,000 miles per hour. Humans can withstand this velocity in this type of shuttle, but if the shuttle even attempted to approach the speed of light, the effect would prove fatal to astron

The first obstacle the writers had to confront is much simpler than you'd think. One of the most important things you need to know before understanding warp speed is actually one of the oldest tricks in the physics book, Newton's Third Law of Motion. You've probably heard it before -- this law states that for every action, there is an equal and opposite reaction. It simply means that for every interaction between two objects, a pair of forces is working on both of them. For instance, if you roll one billiard ball straight into another one that's at rest, they will both exert an equal force on each other. The moving ball will hit the ball at rest and push it away, but it will also be pushed back by the latter.

You feel this law come into play every time you accelerate in a car or fly in an airplane. As the vehicle speeds up and moves forward, you feel pressure on your seat. The seat is pushing on you, but you're also exerting a force against the seat.

So what does this have to do with "Star Trek" and the Enterprise? Even if it were possible to accelerate to something like half the speed of light, such intense acceleration would kill a person by smashing him against his seat.
­ Even though he'd be pushing back with an equal and opposite force, his mass compared to the starship is just too small -- the same kind of thing happens when a mosquito hits your windshield and splatters. So how can the Enterprise possibly go faster than the speed of light without killing the members on board?

In the next section, we'll see how the "Star Trek" creators began to get around the problem of sending matter through space at superluminal speeds.

Einstein, Relativity and the Space-time Continuum

In order to sidestep the issue of Newton's Third Law of Motion and the impossibility of matter traveling faster than the speed of light, we can look to Einstein and the relationship between space and time. Taken together, space, consisting of three dimensions (up-down, left-right, and forward-backward) and time are all part of what's called the space-time continuum.

It's important to understand Einstein's work on the space-time continuum and how it relates to the Enterprise traveling through space. In his Special Theory of Relativity, Einstein states two postulates:

The speed of light (about 300,000,000 meters per second) is the same for all observers, whether or not they're moving.

Anyone moving at a constant speed should observe the same physical laws.

Putting these two ideas together, Einstein realized that space and time are relative -- an object in motion actually experiences time at a slower rate than one at rest. Although this may seem absurd to us, we travel incredibly slow when compared to the speed of light, so we don't notice the hands on our watches ticking slower when we're running or traveling on an airplane. Scientists have actually proved this phenomenon by sending atomic clocks up with high-speed rocket ships. They returned to Earth slightly behind the clocks on the ground.

What does this mean for the Captain Kirk and his team? The closer an object gets to the speed of light, that object actually experiences time at a significantly slower rate. If the Enterprise were traveling safely at close to the speed of light to the center of our galaxy from Earth, it would take 25,000 years of Earth time. For the crew, however, the trip would probably only take 10 years.

Although that timeframe might be possible for the individuals onboard, we're presented with yet another problem -- a Federation attempting to run an intergalactic civilization would run into some problems if it took 50,000 years for a starship to hit the center of our galaxy and come back.

So the Enterprise has to avoid the speed of light in order to keep the passengers onboard in synch with Federation time. At the same time, it also must reach speeds faster than that of light in order to move around the universe in an efficient manner. Unfortunately, as Einstein states in his Special Theory of Relativity, nothing is faster than the speed of light. Space travel therefore would be impossible if we're looking at the special relativity.

According to Einstein's General Theory of Relativity, matter bends the fabric of space and time. The distortion of the space-time continuum even affects the behavior of light.

That's why we need to look at Einstein's later theory, the General Theory of Relativity, which describes how gravity affects the shape of space and flow of time. Imagine a stretched-out sheet. If you place a bowling ball in the middle of the sheet, the sheet will warp as the weight of the ball pushes down on it. If you place a baseball on the same sheet, it will roll towards the bowling ball. This is a simple design, and space doesn't act like a two-dimension bed sheet, but it can be applied to something like our solar system -- more massive objects like our sun can warp space and affect the orbits of the surrounding planets. The planets don't fall into the sun, of course, because of the high speeds at which they travel.

On the next page, we'll see how this comes into play on the Enterprise.

The Warp Drive

The ability to manipulate space is the most important concept in regard to warp speed. If the Enterprise could warp the space-time continuum by expanding the area behind it and contracting the area in front, the crew could avoid going the speed of light. As long as it creates its own gravitational field, the starship could travel locally at very slow velocities, therefore avoiding the pitfalls of Newton's Third Law of Motion and keeping clocks in sync with its launch site and destination. The ship isn't really traveling at a "speed," per se -- it's more like it's pulling its destination toward it while pushing its starting point back.

A warp bubble surrounding a starship, which protects the ship and crew members as space and time distorts.

Because the ideas behind Einstein's General Theory of Relativity are complex and still open to interpretation, this leaves the possibilities wide open for science fiction writers. We may not know how to bend space and time with our current technology, but a fictional civilization set in the future may be completely capable of inventing such a device with the right imagination.

In the "Star Trek" universe, warp speed is accomplished through the use of a warp drive. The warp drive is powered by matter-antimatter reactions, which are regulated by a substance called dilithium. This reaction creates highly-energetic plasma known as electro-plasma, a type of matter with its own magnetic field, which reacts with the starship's warp coils. The warp coils are typically enclosed in what the "Star Trek" writers call a warp nacelle. The whole package creates a "warp field" or "bubble" around the Enterprise, allowing the ship and its crew to remain safe while space manipulates around them.

Sometime between the first television series ("Star Trek: The Original Series") and the second ("Star Trek: The Next Generation"), the writers decided to assign a limit to warp speed -- using a scale of Warp-1 to Warp-10, the Enterprise wasn't allowed to travel just anywhere at anytime, seeing as that would make plotting too easy. In the show, Warp-10 became an impossible maximum speed, an infinity in which the starship would be at all points in the universe at the same time. Warp-9.6, according to the "Next Generation" technical manual, is the highest attainable speed allowed -- it's set at 1,909 times the speed of light. Although there are some inconsistencies, the following list the different speeds in the "Star Trek" universe:

Warp Factor

Number of times the speed of light

1

1

2

10

3

39

4

102

5

215

6

392

7

656

8

1,024

9

1,516

9.6

1,909

10

Infinity

In the next section, we'll take a look at some of the problems the concept of warp speed encounters.

So Einstein helped the "Star Trek" writers manipulate space in a science fictional universe, but is it actually possible to build a spaceship that could propel people across vast galaxies in a relatively short period of time?

Physicist Miguel Alcubierre has suggested the use of so-called "exotic matter," a theoretical type of matter with negative energy. If it could be found or created, the exotic matter would do the job of repelling space and time and creating the gravitational field.

Unfortunately, that's as far as it goes for possible fuel sources -- there are more problems than solutions when it comes to the concept of powering warp speed. Even if the Enterprise were to travel at sublight speeds, known as impulse drive to "Star Trek" fans, the amount of fuel and energy needed to travel quickly through space would be too much for a single starship. The impulse drive of the Enterprise is powered by nuclear fusion, the same kind of reaction that lights up the sun and creates huge explosions from certain nuclear bombs. According to Dr. Lawrence Krauss, a theoretical physicist and author of "The Physics of Star Trek," if Captain Kirk wanted to travel at half the speed of light (150,000 kilometers per second), the starship would need to burn 81 times its mass in hydrogen, the fuel used for nuclear fusion. The technical manual for "Star Trek: The Next Generation" lists the Enterprise as more than 4 million metric tons in weight, so the ship would need more than 300 million metric tons of hydrogen just to move forward. Of course, to slow down to a stop, the starship would need yet another 300 million metric tons of fuel, and a potential trip across galaxies would need 6,642 times the mass of the "Enterprise."

Some people have proposed a system in which a device gathers hydrogen as the starship travels, foregoing the necessity to store huge amounts of fuel, but Krauss suggests this device would have to be about 25 miles wide to capture anything worth using. Even though hydrogen is the most abundant element in the galaxy, there's only about one atom of hydrogen for every cubic square inch.

Making the warp drive work would be another thing. The warp drive in "Star Trek" gets its power by reacting matter with antimatter -- the result is complete annihilation and the release of pure energy. Since antimatter isn't very common throughout our universe, the Federation would have to produce it, something we can do today at the Fermi National Accelerator Laboratory (Fermilab) in Illinois. Again, the problem turns out to be a issue of the amount of fuel necessary to power a warp drive. Kruass notes that Fermilab is capable of producing 50 billion antiprotons in one hour -- enough to produce 1/1000 of a watt. You would need 100,000 Fermilabs to power a single light bulb. Producing enough antiprotons to bend the space-time continuum looks near impossible as far as our current technology goes.

Although there's little chance during this century of humans developing a spaceship that could bend space and travel to distant galaxies faster than the speed of light, this hasn't stopped scientists and fans of the series alike to think about the potential. As recent as November 2007, the British Interplanetary Society brought together several physicists for a conference called "Faster Than Light: Breaking the Interstellar Distance Barrier" [source: Guardian].

The Science of "Star Trek"

As far as science fiction goes, "Star Trek" is well regarded by its
fans for sticking to relatively plausible physics. Although no one's
come up with a starship that would travel at warp speed, no one's
disproved the possibility of such a feat. "Star Trek" has also looked
at other big concepts throughout the series, including the notion of time travel through black holes
or wormholes. The writers also get several nitpicky details correct,
such as the fact that there is no sound in space. While George Lucas
includes laser blasts and explosions throughout his "Star Wars" series
in order to keep things dramatic, "Star Trek" kept a bit closer to
reality by not including sound effects in space.

For lots more information on space and intergalactic travel, see the next page.